Differential signaling is a method of transmitting information electrically by means of two complementary signals sent on two separate lines. The technique can be used for both analog signaling, as in some audio systems, and digital signaling, as in RS-422, RS-485, Ethernet (twisted-pair only), PCI Express and USB. The opposite technique, which is more common but lacks some of the benefits of differential signaling, is called single-ended signaling.
In differential signaling, at one end of a transmission channel connection, a receiving device reads the difference between the two signals. Since the receiver ignores the wires' voltages with respect to ground, small changes in ground potential between transmitter and receiver do not affect the receiver's ability to detect the signal.